Cognitive impairment is a comorbidity of many neurological diseases of the central nervous system, including multiple sclerosis. Multiple sclerosis affects over 2 million individuals worldwide. The most commonly and severely affected facets of cognition in multiple sclerosis patients are attention, anterograde episodic memory, processing speed, and visuospatial memory. Patients with progressive forms of multiple sclerosis are more commonly and severely affected by cognitive impairment than relapsing remitting multiple sclerosis patients, but overall disease severity has a very weak correlation with the presence of and/or severity of cognitive impairment.
A number of factors have been implicated as potentially contributing to cognitive impairment in multiple sclerosis patients, including global brain atrophy, genetic risk factors, dysregulated signaling pathways and accelerated inflammatory processes. However, the symptom variability in multiple sclerosis patients with cognitive impairment ranges from slight memory disturbances to complete dementia, and there is not a strong correlation between lesion load and the presence and/or severity of cognitive comorbities. These factors, combined with researchers' incomplete understanding of the molecular mechanisms behind cognitive impairment in neurological diseases, such as multiple sclerosis, have prevented the development of efficacious drug therapies.
The development of novel and effective treatments for cognitive impairment in MS could benefit over 1 million people worldwide. MS patients who are affected by cognitive impairment early in disease progression are more prone to severe learning and memory impairments later in life. The average age of MS onset is relatively young compared to other neurodegenerative disorders, approximately 20-40 years of age, and MS is the second leading cause of neurological disability in young adults in the United States. An estimated 50-80% of all MS patients are unemployed within 10 years of disease onset. Thus, early detection and treatment of cognitive impairment in MS would greatly improve the quality of life of many MS patients.
Thus, there exists a great need for diagnostic tests to identify neurological disease patients at risk for cognitive impairment and for novel compositions and methods for the treatment of cognitive impairment in neurological disease patients, such as patients with multiple sclerosis.